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Cascading transistorsMiguel (mcleod_ideafix) alerted me on an aspect of a design I'm working on where I am cascading transistors, which may give problems. This is the par…
... supply has to raise its voltage supply. When it's ... CPU clock and reading lower RAM to display the image. ... ROM and upper RAM are also available at this ... supply rails to feed lower RAM. The DC-DC converter ... from nowhere because lower RAM won't be ready ... -
Spectrum +2(grey) rf problem not tuning inHi lads, first of all a quick intro. Im a speccy enthusiast in Ireland, had my first speccy when i was seven in 1987(grey +2). Eventually it got repl…
... lower RAM chips, the ZTX651 mentioned is simply a higher voltage device ... -
16K/48K Lower RAM (4116) replacement.You may want to read [URL="http://www.worldofspectrum.org/forums/showthread.php?t=37957"]this thread[/URL] for background information on the quest t…
... new heatsink compound to the regulator/heatsink junction, reseat all the ... need to swop out the RAM, ROM, CPU if it's ... -
16K/48K Lower RAM (4116) replacement.You may want to read [URL="http://www.worldofspectrum.org/forums/showthread.php?t=37957"]this thread[/URL] for background information on the quest t…
... also add the 7805 power regulator as something than I would ... helps the 7805 regulator by having to drop less voltage across it ... -
16K/48K Lower RAM (4116) replacement.You may want to read [URL="http://www.worldofspectrum.org/forums/showthread.php?t=37957"]this thread[/URL] for background information on the quest t…
... the original PSU? The Recom regulator at least it is not ... two rectifiers to lower the voltage is sensible enough but with ... -
Poorly Issue One 16k spectrum diagnosis?Hello, everyone. :smile: I was lucky enough to buy an Issue One 16k rubber key the other week; I didn't know it was an Issue One till I opened it up…
... display data from the lower RAM. I encountered many variations of ... it while developing the lower RAM replacement module. Are you using ... ULA can't push the voltage high enough on one or ... -
Poorly Issue One 16k spectrum diagnosis?Hello, everyone. :smile: I was lucky enough to buy an Issue One 16k rubber key the other week; I didn't know it was an Issue One till I opened it up…
... display data from the lower RAM. I encountered many variations of ... it while developing the lower RAM replacement module. Are you using ... ULA can't push the voltage high enough on one or ... -
Issue 2 crashes after about 30 minsHi Guys, I have an Issue 2 zx spectrum that seems to get graphic corruption after about half hour of playing, then finally falls over and crashes. …
... , is measure the off-load voltage being given out by the ... in series to take the voltage down from whatever it is ... is a replacement switch mode regulator available that runs cold, I ... -
Issue 2 crashes after about 30 minsHi Guys, I have an Issue 2 zx spectrum that seems to get graphic corruption after about half hour of playing, then finally falls over and crashes. …
... tomorrow and check the output voltage of my sinclair adaptor. ... these show a higher voltage until a load is ... for the change in voltage between load and no ... mode to measure the voltage of the power supply ... that the input voltage to the regulator may be to ... -
Issue 2 crashes after about 30 minsHi Guys, I have an Issue 2 zx spectrum that seems to get graphic corruption after about half hour of playing, then finally falls over and crashes. …
The output voltage will decrease with increasing current ... 's output impedance. The average voltage also decreases a bit because ... of the ZX Spectrum upper RAM module is working on the ... -
Issue 2 crashes after about 30 minsHi Guys, I have an Issue 2 zx spectrum that seems to get graphic corruption after about half hour of playing, then finally falls over and crashes. …
... talking. If you measure the voltage of the power supply (as ... transformer is loaded, the output voltage of the transformer will fall ... (resistance in the coil) and voltage drop due to changes in ... the voltage first to 9V. I also removed the internal 7805 regulator ... -
Issue 2 crashes after about 30 minsHi Guys, I have an Issue 2 zx spectrum that seems to get graphic corruption after about half hour of playing, then finally falls over and crashes. …
... idea to do a pre-regulator design, then people less knowledgeable ... simply have a wide supply voltage tolerance - but sod's law ... />
@Gaz
Yep - over-voltage PSU. In light of the ... and drop the voltage some more until the pre-regulator gets built ... -
Issue 2 crashes after about 30 minsHi Guys, I have an Issue 2 zx spectrum that seems to get graphic corruption after about half hour of playing, then finally falls over and crashes. …
... idea to do a pre-regulator design, then people less ...
@Gaz
Yep - over-voltage PSU. In light of the ... and drop the voltage some more until the pre-regulator gets built ... a low voltage drop regulator and needs a higher input voltage to function ... -
Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... voltage for video switching, audio on scart
- 5V 2A / switching regulator ... -
Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... voltage for video switching, audio on scart
- 5V 2A / switching regulator ... -
Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... voltage for video switching, audio on scart
- 5V 2A / switching regulator ... -
Opus Discovery PSU[IMG]http://www.scotek.net/zx spectrum/opus.jpg[/IMG] This is a photo of my Opus Discovery transformer. Can anyone tell me what the connections are …
... the left side is low voltage and have recorded what goes ... where the rectifiers/diodes and regulator reside, then I think you ... -
Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... be measured.
Using static RAM and HCT/HC logic ICs ... including sound and video switching voltage.
The first batch of ... -
When is a 16k not a 16k ?Can anyone explain what this machine is supposed to be ? Speccy with a 16K sticker on the base. Doing a peek 23733 returns 255 so a 48K ? Opened …
... issue 2 Spectrums had the voltage converter modification made at the ... bodged to use OKI upper RAM (soldered in place), but I ... -
Linking spectrums - parralel processing is it possible?Was there any way to do this, (excluding disk, tape and microdrives)?
... 32K and replace with shared RAM/ROM.
Part of this ... , one could use dual-ported ram with some logic to pull ... enough ram and i/o and able to handle the voltage?
Linking spectrums - parralel processing is it possible?Was there any way to do this, (excluding disk, tape and microdrives)?
... , one could use dual-ported ram with some logic to pull ... enough ram and i/o and able to handle the voltage?
ZX-Uno prototype for saleThis is a FPGA based clone. You will receive the PCB and all the components unmounted. Mounting this PCB require advanced soldering skills because sm…
... oscillator.
[*]Three voltage regulators.
[*]CY62148EV30, 512Kb of RAM.
[*]W25X40BV ...Another broken SpeccyHi all I have been given another ZX Spectrum, this time it has a really odd problem as you can see in the video: [URL="http://youtu.be/ZOSiBEYQD7w"…
... to check the 4116 lower RAM chips to make sure that ... phut if one of the voltage components is incorrect.
Issue 3 board with strange piggy-back boardIn case you are interested. I?ve never seen something like this before. I have an Issue 3 board here. When I opened the case and found a strange pig…
... Spectrum is using to detect RAM (and subsequently set the 23733 ... power-up so if the voltage of its output is higher ... be confused.
Now, that RAM upgrade *could* require the user ...Issue 3 board with strange piggy-back boardIn case you are interested. I?ve never seen something like this before. I have an Issue 3 board here. When I opened the case and found a strange pig…
... hard to write a simple RAM-checking programme (even in BASIC ... be enough, to read the voltage on IC26 pin 10 and ...Issue 3 board with strange piggy-back boardIn case you are interested. I?ve never seen something like this before. I have an Issue 3 board here. When I opened the case and found a strange pig…
... ). First, on power-up, what voltage is it at? Then type ... simple programme to test the RAM; the upper 32k begins at ... again, to verify that all RAM chips are working. Then, you ... do another "IN" and change RAM page and re-read the ...First time capacitor replacementHi, I have an Issue 2 board, that i wish to start with recapping as advised on here, as they look to be all original. (Same with V3 board, but going…
The low +12v rail voltage is a worry alright, although ... typical pattern of a lower RAM failure any more.
RAM area.
You could ...First time capacitor replacementHi, I have an Issue 2 board, that i wish to start with recapping as advised on here, as they look to be all original. (Same with V3 board, but going…
... ;731550]The low +12v rail voltage is a worry alright, although ... typical pattern of a lower RAM failure any more.
RAM area.
You could ... ?
Ill check the voltage as suggested on pin8 later ...One more grey +2 with video problemsI guess I need your help again to hopefully be able to do some proper troubleshooting myself one day. Here I have a grey +2, which could be a bottom…
... measuring the voltage from the correct pins of the regulator? 5V should ... have 5V going INTO a regulator and near expected supply ... output.
Check the voltage output of the PSU - 10 ... shorted out and dragging the voltage down. Anything getting hot? ...eBay 128K Spectrum RGB cables overheat the Spectrum!?Hi everybody, For a long time I've wondered why Spectrum 128K Toastracks were overheating when using my Retro Computer Shack RGB SCART cable. Today …
... low and affects the output voltage from the ULA (as shown ... . not related to the discussion: RAM tester ROM has been just ...
